The present invention relates to a method for installing an electric machine, in particular a generator for a wind turbine generator system. The present invention also relates to such an electric machine with a stator and a rotor.
Wind turbine generator systems are generally equipped with relatively large generators. These generators are often not installed until they are on site. This applies in particular to two components of the generator, namely the rotor and the stator. This is irrespective of whether an external stator and internal rotor are used, or an external rotor and internal stator.
Since the rotor is normally equipped with permanent magnets it constantly exerts a magnetic force on the stator components. The consequence is that the components of the stator are difficult to position and install opposite the components of the rotor. These problems are particularly severe for direct-drive wind turbines that have a very large diameter.
Up to now, there have been installation methods in which the rotor is preinstalled as a complete unit and, in the case of an internal rotor, is then surrounded on site with stator segments which together constitute a complete stator ring. Such segmented machines have a joint between the segments. Before the segments are bolted the joints have to be padded out with plates of appropriate thickness to produce a continuous ring. This padding of the joints calls for great skill and experience. It often presents problems on site in the open air.